Moving coil relay



Feb. 25, 1958 w, DASCHKE 2,824,926

MOVING COIL RELAY Filed Oct. 15, 1954 2 Sheets-Sheet l Q W 1 mm Huang? IN V EN TOR.

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MOVING COIL RELAY Filed Oct. 13, 1954 2 Sheets-Sheet 2 FIG-7 IN VEN TOR. ARTHUR W. DHSCHKE ATTORNEYS United States Patent MOVING COIL RELAY Arthur W. Daschke, Denville, N. Triplett' Electrical Instrument corporation of Ohio J., assignor to The Co., Blutrton, Ohio, :1

This invention relates to electrical instruments, and particularly to contact making electric instruments, or, as they are more customarily referred to, instrument type relays.

Relays of the nature referred to above are generally in the form of an electrical instrument movement, which may advantageously be a DArsonval moving coil type of movement. An instrument movement of this nature can be made extremely delicate so that it will move substantial distances under the influence of extremely small currents and voltages.

In utilizing movements of this nature to construct sensitive relays, the movement isarranged to carry a moving' contact adapted for engaging a stationary contact to close a control circuit. Inasmuch as the force with which such a delicately balanced coil is moved is extremely small these instruments normally employ means for increasing the pressure between the contacts after they have closed, or means are provided for pulling the contacts together under pressure when the moving contact reaches a predetermined position of proximity with the stationary contact.

This function is generally accomplished by providing magnets associated with the contacts which will produce the desired contact pressure so that the relay will provide reliable contact operation.

Another method of obtaining the desired contact pressure has been to supply a second winding on the moving coil connected to a circuit under the control of the contacts which will be energized at the instant the contacts meet and the energization of which winding will bias the coil to produce the desired contact pressure.

Both of the arrangements referred to above have disadvantages in that the use of additional magnets associated with the contacts is an added expense and requires careful positioning and adjusting of the magnets relative to the contacts. The arrangement where an auxiliary winding is employed has the obvious disadvantage of added weight, size and complexity of the moving coil, is expensive, and requires an auxiliary circuit for the second winding and also requires that the contacts actually come together in current-conducting relation before the auxiliary winding will be energized to provide for the desired contact pressure.

Having the foregoing in mind, the present invention has as its particular object the provision of a sensitive instrument type relay in which the foregoing drawbacks and disadvantages of conventional relays of this nature are eliminated.

Another particular object of the present invention is to provide a simple inexpensive arrangement in the sensitive instrument type relay, but which will provide for positive and reliable operation of the relay at all times.

A further object of the present invention is the provision of a sensitive instrument type relay in which the adjustment of the contacts and contact-closing magnet means can easily be elfected.

2,824,926 Patented Feb. 25, 1958 A particular and still further object of the present invention is the provision of an instrument type relay having magnetically-operated means for creating contact pressure, but which magnetic means does not require the use of extra magnets as has heretofore been done.

These and other objects and advantages of this invention will become more apparent upon reference to the following specification taken in connection with the accompanying drawings, in which:

Figure 1 is a front elevational view of an instrument type relay according to the present invention with a portion of the cover removed therefrom;

Figure 2 is a rear view of the instrument of Figure 1, with a portion of the case broken away to show the movement;

Figure 3 is a diagrammatic perspective view showing the important elements of the instrument movement and the contact-making elements of the relay;

Figure 4 is a view showing the elements making up the magnetic means by which the contacts of the relay are urged into pressure relation;

Figure 5 is a sectional view indicated by line 5-5 on Figure 1 showing how the stationary contact elements are insulatingly supported on the dial of the relay;

Figure 6 is a view showing how an electrical connection is made between a wire of the control circuit and the moving contacts that are carried on the instrument pointer;

Figure 7 is a vertical sectional view indicated by line 7--7 on Figure 1;

Figure 8 is a view showing the lower pivot structure for the moving coil of the instrument and the manner in which electrical connection is effected with the winding of the moving coil;

Figure 9 is a view showing a manual arrangement for moving the pointer of the instrument away from contactmaking position when it is desired to break the control circuit closed by the contacts; and

Figure 10 is a perspective view showing a modified structure according to the present invention employing permanent magnets.

Referring to the drawings somewhat more in detail, the instrument type relay according to this invention comprises a case 10 having a transparent cover 12 mounted thereon, and located within the case is an instrument movement generally indicated at 14 which may be a movement of any type embodying a movable element, but which, preferably, is a DArsonval type movement that comprises a magnet frame 16 and the legs 18 extending therefrom which are in opposed relation so that there can be mounted therebetween a core 20 about which is supported a bobbin or coil frame on which the coil 22 is wound.

The movement also comprises a dial 24 over which a pointer 26 attached to the coil 22 moves.

As will be seen in Figures 3 and 7, the coil is provided with shaft means 28 by which the moving coil and pointer assembly is rotatably supported as by means of the jeweled pivot screws 30. The pivot screws are carried in a frame arrangement 32, which is also utilized for supporting the core 20, as will be seen in Figure 7.

Between the pointer 26 and the upper bridge member 34 of the frame 32 is a spiral biasing spring 36, one end of which is fixed to the adjacent shaft means 28 and the other end of which is connected with the end of zero adjusting lever 38, which is movably secured to bridge member 34 by a clamp nut and spring washer arrange ment 40 mounted on the adjacent pivot screw 30.

The described arrangement is availed of for making electrical connection with pointer 26 by connecting a wire 42 to bridge member 34, whence electrical contact is made through lever 38 and spring 36 and adjacent shaft means28 to pointer 26.

The shaft means 28, at the bottom of the coil, mounts two spiral springs as at 44 and 46 in Figures 7 and 8, and these springs are availed of for effecting electrical connection with Opposite ends of moving coil 22. Springs 44 and 46, rather than being electrically connected with associated shaft means 28, are insulatingly connected thereto while fine lead wires, as at 48 and 50, lead from the respective springs to the opposite ends of coil 22.

The outer ends of springs 44 and 46 are connected to the levers 52 and 54, respectively, and surround the adjacent pivot screw 30 and are insulated from each other and from the said pivot screw, and from the lower bridge member 56 of frame 32, and also from a clamp nut 58 on the screw 30 by a plurality of insulating washers and bushings generally indicated at 60, as illustrated in Figure 8. Leading to the levers 52 and 54 are the wires 62 and 64 which carry the electrical energy that actuates the moving coil.

The instrument movement is supported in case by a pair of studs 66 extending through the back wall of the case, as will best be seen in Figure 7, and which studs are mounted in a plastic block 68 secured to the magnetic frame of the instrument, and the nuts 70 on studs 66 clamp the movement to the back wall of the case.

The studs 66 are advantageously employed as lead-ins for the electrical energy which actuates the moving coil, and to this end the wires 62 and 64, previously referred to as being connected to opposite ends of the moving coil, are electrically connected with studs 66, as will be seen in Figure 2.

The back wall of the case also receives the studs 72, 74 and 76, the center one of which (Figure 2) is connected to wire 42 leading to the instrument pointer, while the outer two are connected with stationary contacts carried on the dial of the movement.

The stationary contacts, as will be seen in Figures 1, 3 and 5, are in the form of small slotted plates 78 having end portions extending toward pointer 26 and carrying contact elements 80. The plates 78 are insulatingly supported on dial 24 by the insulating washer means 82 and screws 84. The slots in the contact plates provide for adjustment thereof toward and away from pointer 26.

the instrument-pointer toward a contact-making position, as soon as the contact elements approach a position of proximity the magnetic attraction existing between element 92 and the nearest magnetic portion 96 will cause the contact elements to be pulled together under substantial pressure. Thus, magnetic means are provided for bringing the contact elements together and holding them together under pressure without the use of auxiliary secondary windings on the moving coil and without the use of auxiliary permanent magnet elements. Instead, a portion of the magnetic flux from the instrument frame is by-passed into the magnetic arms 94 and creates the contact-closing force desired.

It will be evident that,once the contact elements have been closed, they must be separated before the pointer can return to its zero position. This can be accomplished a number of difiierent ways, and for this purpose there is shown a two-finger wire bracket 106 on a shaft 108 having a knob 110, which knob can be pressed inwardly to locate the ends of the wire bracket means 106 adjacent the end of the pointer, whereupon turning of knob 110 in the right direction will dislodge the pointer from its contact means position.

It will be understood that other means, such as an electrically actuated device (solenoid-operated plunger or the like) could be employed for separating the contacts instead of the manual arrangement described above.

Figure 10 shows a modification wherein permanent magnet means are provided at 120 adjustably secured in the ends of the support arms 122 that are attached to the magnetic frame 124 of the instrument. The arms 122 in the Figure 10 modification are preferably of nonmagnetic material. The permanent magnets 1 20 cooperate with the magnetic elements 126 on the lower counterbalance arm the same as was previously described, and the magnetic elements 126 will rest in close proximity with one or the'other of the permanent magnets 120 when Pointer 26 has secured thereto a fingerlike metal member 86 that has on each side thereof a resilient arcuate finger 88 terminating in a point which will engage the contact element 80 on the same side of the pointer 26 when the pointer is moved in that direction.

. According to the present invention the counterbalance arm 90 of the pointer extending downwardly therefrom has mounted thereon a magnetic element 92 which is preferably soft iron. This element is adapted for cooperation with magnetic elements located on opposite sides of the center of the instrument, and each taking the form of an arcuate arm 94 of magnetic material having its one end pivotally supported on the magnetic frame of the instrument against one of the pole pieces of the magnetic frame whereby the areas are excited by the permanent magnetism of the magnetic frame of the instrument. In the same place as the magnetic element 92 on the counterbalance arm, the arms 94 carry the magnetic portions 96. There is, preferably, a non-magnetic washer 98 between the end of each magnetic arm 94 and its magnetic member 96 so that the flux density of magnetic member 96 may be controlled.

As will be seen in Figure 4, there is also mounted on the lower face of frame 30 a T-shaped magnetic piece 100 arranged in spaced relation to frame 30 by the washer means 102 and secured by the frame of screws 104.

In operation, after the stationary contacts are adjusted to the proper position the magnetic arms 94 are. adjusted so that, when the contact elements are closed, there is at least a small air gap between the magnetic element 92 on the end of the pointer and the magnetic member 96 to which it is adjacent. f

It will be evident that, thereafter, upon movement of the movable contact means 128, carried by instrument pointer 130, engages one or the other of stationary contact elements 132.

The Figure 10 modification, similarly to the first described modification, has the magnetic pressure-developing means remote from the contacts which it influences, and the arrangement of the moving contacts and the magnetic element on the pointer and counterbalance arm of the movement is also, as previously described, on opposite sides of the axis of rotation of the moving coil, thereby to minimize the problem of balancing the moving coil and making the coil lighter and, therefore, more sensitive than if the contacts and magnetic pressure-developing means were on the same side of the axis of rotation of the moving coil.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

I claim:

1. In a sensitive relay; an instrument movement having a permanent magnet frame with opposed pole faces and a coil movably suspended between the pole faces, a dial, a pointer carried by the coil to move over the dial, a counterweight arm projecting from the opposite side of the coil from the pointer, a portion of the length of the counterweight arm being magnetic, resilient movable contact means carried by and electrically connected with the pointer, stationary contact means insulatingly carried by the dial positioned to be engaged by the resilient movable contact means on the pointer upon movement of the coil a predetermined distance from its rest position, and magnet means positioned to be approached by the magnetic portion of the counterweight arm to define an air gap therewith as said contacts close, the magnet means and magnetic portion of the counterweight being adapted to be brought into contact thereby to developpressure between said contacts, said magnet means comprising support means and permanent magnet means therein.

2. In a relay; an instrument movement comprising a permanent magnet frame having opposed pole faces, a moving element comprising a coil suspended in the space between said pole faces and carrying a pointer, a contact on the pointer, a fixed contact engageable by the contact on the pointer, a magnetic element on the moving element, a magnetic horn projecting from one of the pole regions of the said frame so its end is in proximity to the magnetic element when the contacts close, and a plate of magnetic material extending between the poles of said frame but spaced therefrom having an edge extending parallel to the plane of movement of said magnetic element and adjacent thereto to alter the magnetic flux between said magnetic horns.

3. In a sensitive relay; an instrument movement having a permanent magnet frame with opposed pole faces and a coil movably suspended between the pole faces, a pointer carried by the coil, a counterweight arm projecting from the opposite side of the coil from the pointer, a portion of the length of the counterweight arm being magnetic, resilient movable contact means carried by and electrically connected with said pointer, stationary contact means positioned to be engaged by the resilient movable contact means on the pointer upon movement of the coil a predetermined distance from its rest position, and magnet means positioned to be approached by the magnetic portion of the counterweight arm to define an air gap therewith as said contacts close, the magnet means and magnetic portion of the counterweight being adapted to be brought into contact thereby to develop pressure between said contacts, said magnet means comprising support means and permanent magnet means therein.

References Cited in the file of this patent UNITED STATES PATENTS 251,177 Buell Dec. 20, 1881 527,092 Ward Oct. 9, 1894 814,501 Allen Mar. 6, 1906 989,420 Reichel Apr. 11, 1911 1,866,436 Weston July 5, 1932 2,014,385 Lamb Sept. 17, 1935 2,262,504 Lamb Nov. 11, 1941 2,302,399 Stimson Nov. 17, 1942 2,598,847 Snell June 3, 1952 2,603,730 Pethes July 15, 1952 

